Today, facial heat emission patterns may be rapidly obtained and quantified using advanced electronic thermography units and new computer programs which have promise of being non-ionizing, non-invasive, low cost, diagnostic alternative for evaluation of craniomandibular disorders, as compared to current diagnostic examinations which use ionizing radiation (plain and tomographic x-ray examinations), expensive technology (CT and MR imaging), or invasive techniques (arthrotomography of the TMJ). Hypothesis to be tested in this diagnostic study: 1. Thermography as a diagnostic test interpreted by experts in blinded trials will be able to distinguish between normal subjects and patients having internal derangements, osteoarthritis, or arthralgia of the TMJ; 2. Computer measurements made using facial thermograms will be able to distinguish between normal and diseased patient populations (internal derangements, osteoarthritis, and arthralgia of the TMJ); 3.Computer measurements will be superior to thermography experts making diagnostic decisions from the same patient thermograms. Design and methods: Target study populations will consist of 4 groups; patients having internal derangement, osteoarthritis, or arthralgia of the TMJ, and normal subjects. Thermography Equipment. Agema 880 thermovision unit; including an infrared scanner control unit, and thermal image computer TIC-8000. Facial Imaging. Right, left; lateral, and frontal thermograms are to be taken on 120 subjects a photographed for diagnostic evaluation. Computerized Image Analysis. Mathematical analysis will be made from electronic images using TIC-8000 computer and color monitor. Diagnostic Image Assessment. Evaluations will be made in single-blind fashion, independently by 2 examiners, using correct classification rates (sensitivity, specificity). Data Analysis; will include calculating linear discriminent scores from the set of computer measurements for each of the 4 groups. In addition, true-positive and false-positive rates for the observers and the linear discriminant scores will be compared for all diagnostic studies.